Welding or additive manufacturing dual wire drive system

ABSTRACT

A welding or additive manufacturing wire drive system includes a first drive roll having a first annular groove, a second drive roll having a second annular groove, a first welding wire located between the drive rolls in the annular grooves, and a second welding wire located between the drive rolls in the annular grooves. A biasing member biases the first drive roll toward the second drive roll to force the first welding wire to contact the second welding wire. The first welding wire contacts each of a first sidewall portion of the first annular groove, a first sidewall portion of the second annular groove, and the second welding wire. The second welding wire contacts each of a second sidewall portion of the first annular groove, a second sidewall portion of the second annular groove, and the first welding wire. The drive rolls rotate in opposite directions thereby moving the welding wires through the wire drive system.

BACKGROUND OF THE INVENTION Field of the Invention

Devices, systems, and methods consistent with the invention relate tomaterial deposition with a dual wire configuration.

Description of Related Art

When welding, it is often desirable to increase the width of the weldbead or increase the length of the weld puddle during welding. There canbe many different reasons for this desire, which are well known in thewelding industry. For example, it may be desirable to elongate the weldpuddle to keep the weld and filler metals molten for a longer period oftime so as to reduce porosity. That is, if the weld puddle is molten fora longer period of time there is more time for harmful gases to escapethe weld bead before the bead solidifies. Further, it may desirable toincrease the width of a weld bead so as to cover wider weld gap or toincrease a wire deposition rate. In both cases, it is common to use anincreased electrode diameter. The increased diameter will result in bothan elongated and widened weld puddle, even though it may be only desiredto increase the width or the length of the weld puddle, but not both.However, this is not without its disadvantages. Specifically, because alarger electrode is employed more energy is needed in the welding arc tofacilitate proper welding. This increase in energy causes an increase inheat input into the weld and will result in the use of more energy inthe welding operation, because of the larger diameter of the electrodeused. Further, it may create a weld bead profile or cross-section thatis not ideal for certain mechanical applications. Rather than increasingthe diameter of the electrode, it may be desirable to use two smallerelectrodes simultaneously.

BRIEF SUMMARY OF THE INVENTION

The following summary presents a simplified summary in order to providea basic understanding of some aspects of the devices, systems and/ormethods discussed herein. This summary is not an extensive overview ofthe devices, systems and/or methods discussed herein. It is not intendedto identify critical elements or to delineate the scope of such devices,systems and/or methods. Its sole purpose is to present some concepts ina simplified form as a prelude to the more detailed description that ispresented later.

In accordance with one aspect of the present invention, provided is awelding or additive manufacturing wire drive system. The system includesa first drive roll having a first annular groove, and a second driveroll having a second annular groove aligned with the first annulargroove. A first welding wire is located between the first drive roll andthe second drive roll in both of the first annular groove and the secondannular groove. A second welding wire is located between the first driveroll and the second drive roll in both of the first annular groove andthe second annular groove. A biasing member biases the first drive rolltoward the second drive roll to force the first welding wire to contactthe second welding wire. The first welding wire contacts each of a firstsidewall portion of the first annular groove, a first sidewall portionof the second annular groove, and the second welding wire. The secondwelding wire contacts each of a second sidewall portion of the firstannular groove, a second sidewall portion of the second annular groove,and the first welding wire. The first drive roll and the second driveroll rotate in opposite directions thereby moving the first welding wireand the second welding wire through the welding wire drive system.

In accordance with another aspect of the present invention, provided isa welding or additive manufacturing wire drive system. The systemincludes a first drive roll having a first circumferential groovecomprising a first groove base extending between a first inner sidewalland a first outer sidewall of the first circumferential groove. Thesystem further includes a second drive roll having a secondcircumferential groove aligned with the first circumferential groove.The second circumferential groove comprises a second groove baseextending between a second inner sidewall and a second outer sidewall ofthe second circumferential groove. A first welding wire is locatedbetween the first drive roll and the second drive roll in both of thefirst circumferential groove and the second circumferential groove, anda second welding wire is located between the first drive roll and thesecond drive roll in both of the first circumferential groove and thesecond circumferential groove. A biasing member biases the first driveroll toward the second drive roll to force the first welding wire tocontact the second welding wire. The first welding wire contacts each ofthe first inner sidewall, the second inner sidewall, and the secondwelding wire, and the second welding wire contacts each of the firstouter sidewall, the second outer sidewall, and the first welding wire.At least one of the first welding wire and the second welding wire isoffset from both of the first groove base and the second groove base.

In accordance with another aspect of the present invention, provided isa welding or additive manufacturing wire drive system. The systemincludes a first drive roll and a second drive roll. One or both of thefirst drive roll and the second drive roll has a circumferential groove.A first welding wire is located between the first drive roll and thesecond drive roll in the circumferential groove. A second welding wireis located between the first drive roll and the second drive roll in thecircumferential groove. A biasing member biases the first drive rolltoward the second drive roll to force the first welding wire to contactthe second welding wire. The first welding wire further contacts a firstsidewall portion of the circumferential groove, and the second weldingwire further contacts a second sidewall portion of the circumferentialgroove, and both of the first welding wire and the second welding wireare offset from a base portion of the circumferential groove. The baseportion extends between the first sidewall portion and the secondsidewall portion of the circumferential groove.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of the invention will become apparent tothose skilled in the art to which the invention relates upon reading thefollowing description with reference to the accompanying drawings, inwhich:

FIG. 1 is a schematic diagram of an example welding system;

FIG. 2 is a perspective view of an example welding system;

FIG. 3 is a side view of an example wire feeder;

FIG. 4 illustrates an example drive roll;

FIG. 5 is a perspective view of the example drive roll;

FIG. 6 illustrates a cross section of drives rolls feeding dual wires;

FIG. 7 illustrates a cross section of drives rolls feeding dual wires;

FIG. 8 illustrates a cross section of drives rolls feeding dual wires;

FIG. 9 illustrates a cross section of drives rolls feeding dual wires;

FIG. 10 illustrates a cross section of drives rolls feeding dual wires;

FIG. 11 illustrates a cross section of drives rolls feeding dual wires;

FIG. 12 illustrates a cross section of drives rolls feeding dual wires.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the invention will now be described below byreference to the attached Figures. The described exemplary embodimentsare intended to assist the understanding of the invention, and are notintended to limit the scope of the invention in any way. Like referencenumerals refer to like elements throughout.

Embodiments of the present invention are described herein in the contextof a welding system. Example welding systems include gas metal arcwelding (GMAW) systems, submerged arc welding (SAW) systems, flux-coredarc welding (FCAW) systems, metal-cored arc welding (MCAW) systems, andthe like. Further, while the electrodes described herein can be solidelectrodes, embodiments of the present invention are not limited to theuse of solid electrodes. For example, flux-cored electrodes andmetal-cored electrodes can also be used without departing from thespirit or scope of the present invention. Further, embodiments of thepresent invention can also be used in manual, semi-automatic and roboticwelding operations. Because such systems are well known, they will notbe described in detail herein.

Embodiments of the present invention will be discussed in the context ofa welding system. However, in addition to welding operations,embodiments can be used in additive manufacturing processes and otherwelding-type processes involving driven wire electrodes (e.g.,hardfacing).

Turning now to the Figures, FIG. 1 depicts an exemplary embodiment of awelding system 100. The welding system 100 contains a welding powersource or power supply 109 which is coupled to both a welding torch 111and a wire feeder 105. The power source 109 can be any known type ofwelding power source capable of delivering welding current and weldingwaveforms, for example, pulse spray, STT and/or short arc type weldingwaveforms. Because the construction, design and operation of such powersupplies are well known, they need not be described in detail herein. Itis also noted that welding power can be supplied by more than one powersupply at the same time—again the operation of such systems are known.The power source 109 can also include a controller 120 which is coupledto a user interface to allow a user to input control or weldingparameters for the welding operation. The controller 120 can have aprocessor, CPU, memory etc. to be used to control the operation of thewelding process and the generation of welding waveforms. The torch 111,which can be constructed similar to known manual, semi-automatic orrobotic welding torches and can be of a straight or gooseneck type. Thewire feeder 105 draws wire electrodes E1 and E2 from electrode sources101 and 103, respectively, which can be of any known type, such asreels, spools, containers or the like. The wire feeder 105 employs driverolls 107 to draw the electrodes or welding wires E1 and E2 and push orpull the electrodes to the torch 111. Details of the drive rolls 107 arediscussed further below. The drive rolls 107 and wire feeder 105 areconfigured for a dual electrode welding operation. That is, they supplyboth electrodes E1 and E2 simultaneously to the torch 111 for creatingan arc and welding the workpiece W. As shown, the wire feeder 105 isoperatively connected to the power source 109 consistent with knownconfigurations of welding operations.

Once driven by the drive rolls 107, the electrodes E1 and E2 can bepassed through a liner 113 to deliver the electrodes E1 and E2 to thetorch 111. The liner 113 is appropriately sized to allow for the passageof the electrodes E1 and E2 to the torch 111. For example, for two 0.030inch diameter electrodes, a standard 0.0625 inch diameter liner 113(which is typically used for a single 0.0625 inch diameter electrode)can be used with no modification.

In certain embodiment, the wire electrodes E1, E2 can have differentdiameters. That is, embodiments of the present invention can use anelectrode of a first, larger, diameter and an electrode of a second,smaller, diameter. In such an embodiment, it may be possible to moreconveniently weld two workpieces of different thicknesses. For example,the larger electrode can be oriented to the larger workpiece while thesmaller electrode can be oriented to the smaller workpiece. Further,embodiments of the present invention can be used for many differenttypes of welding operations including, but not limited to, GMAW, SAW,FCAW, and MCAW. Additionally, embodiments of the present invention canbe utilized with different electrode types. For example, it iscontemplated that a cored electrode (e.g., flux-cored or metal-cored)can be coupled with a non-cored or solid electrode. Further, electrodesof differing compositions can be used to achieve desired weld propertiesand composition of the final weld bead. Two different, but compatible,consumables can be combined to create a desired weld joint. For example,compatible consumables such as hardfacing wires, stainless wires, nickelalloys and steel wires of different composition can be combined. As onespecific example a mild steel wire can be combined with an overalloyedwire to make a 309 stainless steel composition. This can be advantageouswhen a single consumable of the type desired does not have desirableweld properties. For example, some consumables for specialized weldingprovide the desired weld chemistry but are extremely difficult to useand have difficulty providing a satisfactory weld. However, embodimentsof the present invention allow for the use of two consumables that areeasier to weld with to be combined to create the desired weld chemistry.Embodiments of the present invention can be used to create analloy/deposit chemistry that is not otherwise commercially available, orotherwise very expensive to manufacture. Thus, two different consumablescan be used to obviate the need for an expensive or unavailableconsumable. Further, embodiments can be used to create a diluted alloy.For example, a first welding wire could be a common, inexpensive alloyand a second welding wire could be a specialty wire. The resultingdeposit would be the average of the two wires, mixed well in theformation of a molten droplet, at the lower average cost of the twowires, over an expensive specialty wire. Further, in some applications,the desired deposit could be unavailable due to the lack of appropriateconsumable chemistry, but could be achieved by mixing two standard alloywires, mixed within the molten droplet and deposited as a singledroplet. Further, in some applications, such as the application of wearresistance metals, the desired deposit may be combination of tungstencarbide particles from one wire and chrome carbide particles fromanother. Still in another application, a larger wire housing largerparticles within is mixed with a smaller wire containing fewer particlesor smaller particles, to deposit a mixture of the two wires. Here theexpected contribution from each of the wires is proportional to the sizeof wire. Further, although exemplary embodiments are discussed hereinutilizing two wire electrodes simultaneously, other embodiments of thepresent invention can utilize more than two electrodes. For example, itis contemplated that a three or more electrode configuration can beutilized consistent with the descriptions and discussions set forthherein.

FIG. 2 provides a perspective view of the welding system 100. The wirefeeder 105 comprises drive rolls for conveying wire electrodes E1, E2from electrode sources 101, 103, for use in a particular application.The wire electrodes E1, E2, may be drawn continuously from a reel,spool, or container (e.g., a box or a drum), and delivered to theworkpiece W, which in the current embodiment is a weldment. The wirefeeder 105 may include a drive assembly that utilizes power from one ormore locomotive devices, such as an electric motor, that drive the wireelectrodes E1, E2 to the application work site or workpiece W.

The welding power source 109 may receive electrical input power from anoutside source (e.g., utility power), that is directed to an onboardtransformer and processor-controlled inverter or chopper circuitry, notdepicted in the figures. Output from the power source 109 may beprovided through welding output terminals 121 or studs of the weldingpower source. A welding gun or torch 111 and wire conduit may beelectrically connected to the welding power source 109 through thewelding wire feeder 105 for delivering welding current to the workpieceW in a manner known in the art. It follows that the welding wires E1, E1are fed through the torch 111 and metered out, i.e. dispensed, at thediscretion of the application and/or end user in any manner suitable forconducting the welding process. It is noted that the electrodes E1, E1conduct electricity for establishing a welding arc, wherein theelectrodes are conveyed to the workpiece W having a voltage potentialequal to or approximately equal to the output voltage of the weldingpower source 109, which may be substantially greater than ground.

Different modes of conveying the wire electrodes E1, E2 are known in theart, an example of which includes pushing the electrodes to the torch111 via power or torque provided by the locomotive device. Other modesof conveying the electrodes include push/pull modes that utilizemultiple locomotive devices. The electrodes E1, E2 are delivered to thetorch 111, which may have a trigger or other activation mechanism fordispensing the electrodes at the user's discretion. At times, it may benecessary to deliver the electrodes E1, E2 at varying rates of feed.Therefore, the locomotive device has an output that is adjustable forvarying the wire feed speed (WFS) of the electrodes E1, E2. Inparticular, a drive motor of the wire feeder 105 may be a variable speedmotor to adjust the WFS.

A drive motor 123 is shown in FIG. 3. The wire feeder 105 and/or drivemotor(s) 123 may draw operating power from the welding power source 109,or an altogether separate power source. Still any manner of providingpower to operate the welding wire feeder 105 and/or the drive motors 123may be chosen with sound engineering judgment as is appropriate for usewith the embodiments of the present invention.

Referring to FIGS. 2 and 3, the welding wire feeder 105 may include adrive assembly, or drive roll assembly. As mentioned above, the drivemotor 123, also called a wire feeder motor, delivers power, i.e. torque,to convey the first and second welding wires E1, E2 through the wirefeeder and to the torch 111 and subsequently to the workpiece W. Driverolls 107 are included that grip the welding wires E1, E2 for pushing orpulling the welding wires in the appropriate direction, i.e. toward theworkpiece W. Sets of drive rolls 107 are vertically aligned and havecorresponding aligned annular or circumferential grooves through whichthe wending wires E1, E2 pass simultaneously. It can be seen that thevertically-aligned sets of drive rolls 107 rotate in opposite directionsto drive the welding wires E1, E2 through the wire feeder 105. Forexample, in FIG. 3, the upper drive rolls 107 rotate clockwise and thelower drive rolls rotate counterclockwise. The drive rolls 107 may becylindrical in configuration, or more specifically disk-shaped, althoughthe particular configuration should not be construed as limiting. Thesurface, i.e. the outer circumference, of the driver rolls 107 may becomprised of a sufficiently hardened material, like steel, that isdurable and suitable for gripping the welding wires E1, E2. As shown,the drive rolls 107 may be disposed in pairs along the wire trajectorywith each drive roll of the pair being supported on opposing sides ofthe welding wires E1, E2, such that respective outer circumferentialportions of the rolls engage opposite sides of the wires (e.g., fromabove and below). It is noted that the central axes of respective driverolls 107 extend substantially parallel with one another and generallytransverse to the trajectory of the welding wires E1, E1.

The wire feeder 105 can include a biasing member that biases thevertically-aligned sets of drive rolls 107 toward one another. Thebiasing member sets the clamping force or compression that the driverolls 107 apply to the welding wires E1, E2. For example, the wirefeeder 105 can include biasing springs 125 that apply a bias force toone or more drive rolls 107 to set the compression that the drive rollsapply to the welding wires E1, E2. In the example embodiment of FIG. 3,the biasing springs 125 are mounted to an adjusting rod 127 that can bemoved inward and outward to adjust the compression of the biasingsprings 125. The force of the biasing springs 125 is transferred to theupper drive rolls 107 via pivoting levers 129. As noted above, thevertically-aligned sets of drive rolls 107 have corresponding alignedannular or circumferential grooves through which the wending wires E1,E2 pass simultaneously. That is, the welding wires E1, E2 are locatedtogether in the grooves of an upper drive roll and a lower drive roll.The welding wires E1, E2 are squeezed or compressed within the groovesby the bias force applied by the biasing springs 125 to the drive rolls107. As will be explained further below, the welding wires E1, E2 aremade to contact each other within the grooves when squeezed by the driverolls 107. In addition to an upward/downward compressive force appliedto the welding wires E1, E2, a sideways compressive force is alsoapplied to the welding wires E1, E2 to force them together inside of thegrooves. The sideways compressive force is provided through the shape ofthe sidewalls of the grooves.

Further details regarding the structure of welding wire feeders can befound in U.S. Pat. No. 5,816,466 issued on Oct. 6, 1998 and U.S. Pat.No. 8,569,653 issued on Oct. 29, 2013, both of which are incorporatedherein by reference.

FIGS. 4 and 5 illustrate an example drive roll 107. The drive roll has acentral bore. The inner surface of the bore can include contouredrecesses 131 for receiving projections on a driving mechanism, such as adrive gear, to transfer drive torque to the drive roll 107. The driveroll 107 includes one or more annular or circumferential wire receivinggrooves 133, 135. The wire receiving grooves 133, 135 are spaced axiallyalong the circumference of the drive roll 107. The wire receivinggrooves 133, 135 are designed to receive two welding wires. Examplestandard welding wire diameters for use with the drive rolls 107 include0.030 inches, 0.035 inches, 0.040 inches, 0.045 inches, etc. The wirereceiving grooves 133, 135 can have the same width and depth as eachother, or have different widths and depths to accommodate differentsizes or combinations of dual welding wires. If the wire receivinggrooves 133, 135 each have the same width and depth, then the drive roll107 can be reused when one groove is worn out by simply flipping thedrive roll over and reinstalling it on the wire feeder. The wirereceiving grooves 133, 135 can be configured to simultaneously drive twowires having the same diameter, or two wires having different diameters.In FIG. 4, the wire receiving grooves 133, 135 have a trapezoidal shapewith straight, angled or inwardly-tapered sidewalls and a flat baseextending between the sidewalls. However, the wire receiving grooves133, 135 could have other shapes besides a trapezoidal shape, such ashaving a curved, concave groove base for example. In certainembodiments, the grooves 133, 135 can include knurling or otherfrictional surface treatments to help grip the welding wires.

FIGS. 6 through 11 show partial cross sections of example drive rolls107 as they would be mounted on a wire feeder for supplying dual weldingwires. The drive rolls 107 are biased together to provide a clampingforce on the first E1 and the second E2 welding wires. The welding wiresE1, E2 are both located in the annular grooves of the upper and lowerdrive rolls 107. The annular grooves are aligned and can have atrapezoidal shape. In FIG. 6, the trapezoidal shape is an isoscelestrapezoid formed by an inner sidewall 137, an outer sidewall 139, and agroove base 141 extending between the sidewalls. The isoscelestrapezoidal shape is inverted as a cross-sectional recess from the outercircumferential surface of the drive rolls 107.

Due to the bias force applied to the drive rolls 107, the welding wiresE1, E2 are clamped in the annular grooves between upper and lowersidewalls 137, 139 forming the grooves and the neighboring welding wire.The welding wires E1, E2 are stably held via three points of contactwithin the annular grooves. This clamping system can allow both wires tobe fed through the wire feeder in a consistent manner. The two weldingwires E1, E2 support each other during feeding and pull each other alongvia friction. Because the inner 137 and outer 139 sidewalls of theannular grooves are angled, they apply both vertical and horizontalclamping forces on the welding wires E1, E2. The horizontal clampingforce pushes the welding wires E1, E2 together, causing them to contacteach other. In certain embodiments, the welding wires E1, E2 are clampedwithin the annular grooves so as to be radially offset from both of thegroove bases 141. That is, the welding wires E1, E2 are pinned betweeneach other and the angled sidewalls 137, 139 of the grooves such thatgaps exist between the welding wires and the groove bases 141. This canbe seen clearly in FIG. 6.

The clamping system discussed above allows for some variability (e.g.,due to manufacturing tolerances) in the diameters of the welding wiresE1, E2. If each welding wire E1, E2 had its own dedicated annular groovein the drive rolls 107, and one of the welding wires was slightly largerthan the other, then the smaller welding wire might not be adequatelyclamped between the drive rolls. In such a situation, the larger weldingwire would limit the radial displacement of the drive rolls 107 towardeach other, thereby preventing proper clamping of the smaller wire. Thiscould lead to feeding problems and so-called birdnesting of the smallerwelding wire during feeding. The clamping system discussed above canaccommodate wires of different sizes because the clamping system isself-adjusting. As can be seen in FIG. 7, when one welding wire E1 islarger than the other E2, the contact point between the wires is shiftedaxially from a central position within the annular grooves toward thesmaller wire. Three points of contact are maintained on each weldingwire E1, E2 by the sidewalls 137, 139 of the groove and the neighboringwelding wire.

FIG. 8 shows drive rolls 107 having annular grooves 143 with crosssections having an acute trapezoid shape instead of an isoscelestrapezoid. The inner 145 and outer 147 sidewalls of the grooves havedifferent lengths and form different angles with the outercircumferential surface of the drive rolls. In FIG. 9, the drive rolls107 have annular grooves 149 having a right trapezoid shape. Acute andright trapezoidal grooves can accommodate greater differences in weldingwire diameters than isosceles trapezoids. Thus, acute and righttrapezoidal grooves can be used when the groove is intended to drivewelding wires having different diameters, such as a 0.040 inch weldingwire with a 0.045 inch welding wire. In certain embodiments, thesidewalls and/or base of the grooves can be curved (e.g., concave orconvex). Also, the inside corner transitions between the sidewalls andthe base of the trapezoidal grooves can be curved or radiused. FIG. 10shows example drive rolls having annular grooves with straight, angledsidewalls 150 joined by a concave curved or radiused groove base 152. Inan example embodiment, the angle between the sidewalls 150 and the outercircumference of the drive roll 107 is about 150°, although other anglesare possible and can be determined with sound engineering judgment.

FIG. 11 shows an example embodiment in which one drive roll 107 has atrapezoidal groove for the welding wires E1, E2, and the other driveroll 107 a has a non-trapezoidal groove. In FIG. 10, the non-trapezoidalgroove is rectangular in shape, however other shapes are possible. Forexample, the non-trapezoidal groove could be curved, such as ellipticalor rounded in shape. Further, the trapezoidal groove is shown as beinglocated on the lower drive roll 107. However, the trapezoidal groovecould be located on the upper drive roll 107 a and the non-trapezoidalgroove located on the lower drive roll. The welding wires E1, E2 areclamped between respective sidewalls 137, 139 of the trapezoidal grooveand the base 153 of the non-trapezoidal groove 151, and the weldingwires are forced into contact with each other as discussed above. Thus,the welding wires E1, E2 are stably held via three points of contactwithin the annular grooves 107, 107 a.

FIG. 12 shows an example embodiment in which one drive roll 107 has atrapezoidal groove for the welding wires E1, E2, and the other driveroll 107 b has no groove, but rather directly contacts the welding wireson its outer circumferential surface 155. The trapezoidal groove isshown as being located on the lower drive roll 107. However, thetrapezoidal groove could be located on the upper drive roll. The weldingwires E1, E2 are clamped between respective sidewalls 137, 139 of thetrapezoidal groove and the outer circumferential surface 155 of theupper drive roll 107 b, and the welding wires are forced into contactwith each other as discussed above. Thus, the welding wires E1, E2 arestably held via three points of contact.

It should be evident that this disclosure is by way of example and thatvarious changes may be made by adding, modifying or eliminating detailswithout departing from the fair scope of the teaching contained in thisdisclosure. The invention is therefore not limited to particular detailsof this disclosure except to the extent that the following claims arenecessarily so limited.

What is claimed is:
 1. A welding or additive manufacturing wire drive system, comprising: a first drive roll having a first annular groove; a second drive roll having a second annular groove aligned with the first annular groove; a first welding wire located between the first drive roll and the second drive roll in both of the first annular groove and the second annular groove; a second welding wire located between the first drive roll and the second drive roll in both of the first annular groove and the second annular groove; and a biasing member that biases the first drive roll toward the second drive roll to force the first welding wire to contact the second welding wire, wherein: the first welding wire contacts each of a first sidewall portion of the first annular groove, a first sidewall portion of the second annular groove, and the second welding wire, and the first welding wire is clamped against the second welding wire between the first drive roll and the second drive roll by the first sidewall portion of the first annular groove and the first sidewall portion of the second annular groove, the second welding wire contacts each of a second sidewall portion of the first annular groove, a second sidewall portion of the second annular groove, and the first welding wire, and the second welding wire is clamped against the first welding wire between the first drive roll and the second drive roll by the second sidewall portion of the first annular groove and the second sidewall portion of the second annular groove, and the first drive roll and the second drive roll rotate in opposite directions thereby moving the first welding wire and the second welding wire through the wire drive system.
 2. The welding or additive manufacturing wire drive system of claim 1, wherein the first welding wire and the second welding wire have different diameters.
 3. The welding or additive manufacturing wire drive system of claim 1, wherein the first welding wire and the second welding wire have different compositions.
 4. The welding or additive manufacturing wire drive system of claim 1, wherein the first welding wire is a solid welding wire and the second welding wire is a flux-cored welding wire.
 5. The welding or additive manufacturing wire drive system of claim 1, wherein the first welding wire is a solid welding wire and the second welding wire is a metal-cored welding wire.
 6. The welding or additive manufacturing wire drive system of claim 1, wherein respective cross sections of the first annular groove and the second annular groove have a trapezoidal shape.
 7. The welding or additive manufacturing wire drive system of claim 6, wherein the trapezoidal shape is an isosceles trapezoid.
 8. The welding or additive manufacturing wire drive system of claim 6, wherein the trapezoidal shape is an acute trapezoid.
 9. The welding or additive manufacturing wire drive system of claim 6, wherein the trapezoidal shape is a right trapezoid.
 10. The welding or additive manufacturing wire drive system of claim 1, wherein: the first annular groove comprises a first groove base extending between the first sidewall portion of the first annular groove and the second sidewall portion of the first annular groove, the second annular groove comprises a second groove base extending between the first sidewall portion of the second annular groove and the second sidewall portion of the second annular groove, the first welding wire is offset from both of the first groove base and the second groove base, and the second welding wire is offset from both of the first groove base and the second groove base.
 11. A welding or additive manufacturing wire drive system, comprising: a first drive roll having a first annular groove; a second drive roll having a second annular groove aligned with the first annular groove; a first welding wire located between the first drive roll and the second drive roll in both of the first annular groove and the second annular groove; a second welding wire located between the first drive roll and the second drive roll in both of the first annular groove and the second annular groove; and a biasing member that biases the first drive roll toward the second drive roll to force the first welding wire to contact the second welding wire, wherein: the first welding wire contacts each of a first sidewall portion of the first annular groove, a first sidewall portion of the second annular groove, and the second welding wire, the second welding wire contacts each of a second sidewall portion of the first annular groove, a second sidewall portion of the second annular groove, and the first welding wire, and the first drive roll and the second drive roll rotate in opposite directions thereby moving the first welding wire and the second welding wire through the wire drive system, wherein: the first annular groove comprises a first groove base extending between the first sidewall portion of the first annular groove and the second sidewall portion of the first annular groove, the second annular groove comprises a second groove base extending between the first sidewall portion of the second annular groove and the second sidewall portion of the second annular groove, the first welding wire is offset from both of the first groove base and the second groove base, and the second welding wire is offset from both of the first groove base and the second groove base, and wherein the first welding wire is clamped by the first sidewall portion of the first annular groove, the first sidewall portion of the second annular groove, and the second welding wire so as to be clamped offset from both of the first groove base and the second groove base, and the second welding wire is clamped by the second sidewall portion of the first annular groove, the second sidewall portion of the second annular groove, and the first welding wire so as to be clamped offset from both of the first groove base and the second groove base.
 12. The welding or additive manufacturing wire drive system of claim 1, wherein: the first annular groove comprises a first groove base extending between the first sidewall portion of the first annular groove and the second sidewall portion of the first annular groove, the second annular groove comprises a second groove base extending between the first sidewall portion of the second annular groove and the second sidewall portion of the second annular groove, and respective gaps exists between the first welding wire and both of the first groove base and the second groove base.
 13. A welding or additive manufacturing wire drive system, comprising: a first drive roll having a first circumferential groove comprising a first groove base extending between a first inner sidewall and a first outer sidewall of the first circumferential groove; a second drive roll having a second circumferential groove aligned with the first circumferential groove, wherein the second circumferential groove comprises a second groove base extending between a second inner sidewall and a second outer sidewall of the second circumferential groove; a first welding wire located between the first drive roll and the second drive roll in both of the first circumferential groove and the second circumferential groove; a second welding wire located between the first drive roll and the second drive roll in both of the first circumferential groove and the second circumferential groove; and a biasing member that biases the first drive roll toward the second drive roll to force the first welding wire to contact the second welding wire, wherein: the first welding wire contacts each of the first inner sidewall, the second inner sidewall, and the second welding wire, the second welding wire contacts each of the first outer sidewall, the second outer sidewall, and the first welding wire, the first welding wire is clamped by the first inner sidewall, the second inner sidewall, and the second welding wire so as to be clamped offset from both of the first groove base and the second groove base, and the second welding wire is clamped by the first outer sidewall, the second outer sidewall, and the first welding wire so as to be clamped offset from both of the first groove base and the second groove base.
 14. The welding or additive manufacturing wire drive system of claim 13, wherein the first welding wire and the second welding wire have different diameters.
 15. The welding or additive manufacturing wire drive system of claim 13, wherein the first welding wire and the second welding wire have different compositions.
 16. The welding or additive manufacturing wire drive system of claim 13, wherein one of the first welding wire and the second welding wire is a solid welding wire and another one of the first welding wire and the second welding wire is a flux-cored welding wire.
 17. The welding or additive manufacturing wire drive system of claim 13, wherein one of the first welding wire and the second welding wire is a solid welding wire and another one of the first welding wire and the second welding wire is a metal-cored welding wire.
 18. The welding or additive manufacturing wire drive system of claim 13, wherein respective cross sections of the first circumferential groove and the second circumferential groove have a trapezoidal shape.
 19. The welding or additive manufacturing wire drive system of claim 18, wherein the trapezoidal shape is an isosceles trapezoid.
 20. The welding or additive manufacturing wire drive system of claim 18, wherein the trapezoidal shape is an acute trapezoid.
 21. The welding or additive manufacturing wire drive system of claim 18, wherein the trapezoidal shape is a right trapezoid.
 22. A welding or additive manufacturing wire drive system, comprising: a first drive roll; a second drive roll, wherein one or both of the first drive roll and the second drive roll has a circumferential groove; a first welding wire located between the first drive roll and the second drive roll in the circumferential groove; a second welding wire located between the first drive roll and the second drive roll in the circumferential groove; and a biasing member that biases the first drive roll toward the second drive roll to force the first welding wire to contact the second welding wire, wherein the first welding wire further contacts a first sidewall portion of the circumferential groove, and the second welding wire further contacts a second sidewall portion of the circumferential groove, wherein both of the first welding wire and the second welding wire are offset from a base portion of the circumferential groove, said base portion extending between the first sidewall portion and the second sidewall portion of the circumferential groove, and the first welding wire is clamped by the first sidewall portion of the circumferential groove against the second welding wire so as to be clamped offset from the base portion, and the second welding wire is clamped by the second sidewall portion of the circumferential groove against the first welding wire so as to be clamped offset from the base portion.
 23. The welding or additive manufacturing wire drive system of claim 22, wherein the circumferential groove has a trapezoidal shape.
 24. The welding or additive manufacturing wire drive system of claim 22, wherein the first welding wire and the second welding wire have different diameters.
 25. The welding or additive manufacturing wire drive system of claim 22, wherein both of the first drive roll and the second drive roll include respective vertically-aligned circumferential grooves.
 26. The welding or additive manufacturing wire drive system of claim 22, wherein the base portion of the circumferential groove is concave. 